Normally as a way of explaining poor or shoddy service.
In defence of the place, I have always found exactly the opposite to be true.
During my recent visit, I purchased a wooden door from a company on Petchkasem. I wasn't exactly sure of the size but the lady said she would exchange it if need be.
It was delivered next day, and fitted, exactly when the company said it would be.
The carpenter was extremely professional and did a good job.
I also needed a repair to a window frame. Something as trivial as a single rivet dropping out.
The guys turned up at the agreed time, and within minutes had done the job.
They wouldn't take any payment from me. Apparently, not everyone wants to rip off a Farang.
I can only think those who frequently blast the Thais may have spent rather too long away from their native soil. I know in my neck of the woods, any of the services mentioned above would have taken weeks to arrange, if the people bothered to turn up at all.
Just saying....

BL